Terminal structure for electrical heating unit



Nov. 22, 1960 E. G. HACHMEISTER ETAL 2,951,632

TERMINAL STRUCTURE FOR ELECTRICAL HEATING UNIT Filed June 28. 1956 wmawlmlmw 27 INVENTORS, ERNEST 3. HACHMEiSTER BV Marrow EPSTEKN i 7 04.41@044,

ATTORNEYfi United States Patent TERMINAL STRUCTURE FOR ELECTRICALHEATING UNIT Ernest G. Hachmeister, St. Louis, and Milton Epstein,

University City, Mo., assignors to Industrial Engineering and EquipmentCo., St. Louis, Mo., a corporation of Missouri Filed June 28, 1956, Ser.No. 594,502

2 Claims. (Cl. 339-136) This invention relates to improvements in aterminal structure for a heating unit particularly adapted fordefrosting refrigerators, cooling cabinets, refrigerated show cases andthe like.

It is an important objective of the present invention to provideimproved means in the terminal structure by which terminal prongs aresecurely retained in insulator elements arranged in a casing assembly,such improved means relieving the heating coil from all stress andstrain to which the prongs may be subjected incident to connection anddisconnection of a cooperating female plug.

Another important object is realized by the provision of a pair ofcoacting insulator elements arranged in end to end relation throughwhich the terminal prongs extend, and by the provision of recesses inone element located adjacent the other element, the recesses beingadapted to receive shoulders formed on the prongs so that the shoulderscooperate with the insulator elements to retain the prongs.

Other important advantages are achieved by utilizing an adhesivematerial in the recesses and between the insulator elements, suchmaterial securing the elements together and cooperating with thepreviously described assembly to retain the terminal prongs in positiveconnection with the insulator elements.

Still another important object is afforded by the provision of aninternal shoulder on the tubular casing arranged to engage an abutmenton one of the insulator elements to secure the elements in the casing inspaced relation to one casing end. Other advantages are realized byplacing an insulating material about the terminal prongs from the casingend to the insulator elements.

Yet another object is obtained by constructing one insulator elementwith a reduced end portion adapted to interfit closely the annulardepressed casing shoulder and to extend slightly into the casing portionforwardly of such shoulder, and by placing an insulating material in thecasing around the prongs and reduced element portion whereby to insulatethe prongs from the casing and to retain the elements in assembly.

Other important objects are realized in the provision of a terminalstructure that is simple and durable in construction, economical tomanufacture, and which is readily assembled and connected to the heatingunit to afford a water proof or moisture proof device.

The foregoing and numerous other objects and advantages of the inventionwill more clearly appear from the following detailed description of apreferred embodiment, particularly when considered in connection withthe accompanying drawing, in which:

Fig. 1 is a fragmentary side elevational view of the heating unit shownpartly in cross section;

Fig. 2 is a cross sectional view of the terminal structure as seen alongline 22 of Fig. 1;

Fig. 3 is an enlarged cross sectional view of the internal portion ofthe terminal structure before assembly to the tubular casing, and

2,961,632 Patented Nov. 22, 1960 Fig. 4 is an enlarged, fragmentaryview, partly in cross section as seen along line 4-4 of Fig. 2.

Referring now by characters of reference to the drawing and first toFig. 1, it is seen that the heating unit consists generally of anelongate tubular structure 10 that is usually placed in the cold area ofa refrigerator or refrigated show case, the heating unit being utilizedto defrost the cold area selectively upon attachment of a female plugand the application of eletcric power to energize such unit.

The terminal structure for the heating unit includes a tubular casing 11preferably constructed of brass, which may be an integral part of thetubular structure of the heating unit as is shown in Fig. 1, but may beconstructed as a separate part attached to the tubular structurecarrying the heating elements. The tubular casing 11 is provided with anannular depressed portion 12 that is spaced a distance from the forwardend 13 of the casing, the depressed portion 12 affording an annularinternal shoulder that divides the tubular casing 11 into a forwardcasing chamber 14 and a rearward casing chamber 15.

A pair of insulator elements 16 and 17 are arranged in end to endrelation within tubular casing 11, the elements 1617 having a diameterthat closely approximates the internal diameter of casing 11. Formed ininsulator elements 1617 are a pair of aligned bores 18 that extend fromone end to the other. Formed in each bore 18 of insulator element 16 atthe end adjacent insulator element 17, is an enlarged recess 20 that isslightly larger than the bore diameter.

A terminal prong 21 is received in and extends through each bore 18.Each prong 21 is provided with an enlarged shoulder 22 that is receivedin the recess 20.

In assembling the component parts of the terminal structure, the prongs21 are located in bores 18 of insulator element 16 and the shoulders 22located in recesses 20. The shoulders 22 are particularly located alongthe length of prongs 21 so that they abut element 16 to determine thedesired extension of prongs 21 behind in sulator element 16. After theprongs 21 are disposed in element 16 as described, an adhesive material23 is placed in recesses 20 on the end surface adjacent insulatorelement 17. Then the insulator element 17 is fitted over terminal prongs21 and pressed against insulator element 16, the adhesive material 23securing the elements 1617 together and cooperating with such elementsto retain shoulders 22 in recesses 20. With this construction as isshown in Fig. 3, the terminal prongs 21 and insulator elements 1617 areretained as a unitary structure in which the prongs 21 are preventedfrom moving longitudinally in bores 18 upon application of any stress orstrain applied to such prongs.

The insulator elements 16-17 are located in casing chamber 15 at therear of depressed portion 12, as is more clearly shown in Fig. 4.Insulator element 17 is provided with a reduced forward end portion 24that interfits the annular portion 12 and extends partially into forwardcasing chamber 14. In forming reduced end portion 24, a shoulder 25 isprovided that engages depressed portion 12 to retain the elements 1617in the desired position.

The terminal prongs 21 extend forwardly of element 17, through casingchamber 14 and extend out of forward casing end 13 for selectiveconnection with a female plug (not shown). The portions 26 of terminalprongs 21 ex tending rearwardly of insulator element 16 are providedwith sockets 27 adapted to receive the terminal ends 30 (Fig. 4) of theheating coil generally referred to at 31 in Fig. 1.

With the insulator elements 1617 arranged in the position shown in Fig.4 with reduced end portion 24 interfitted into depressed casing portion12, an insulating material 32 such as molded plastic or rubber isdisposed in the forward casing chamber 14 about terminal prongs 21 andreduced insulator element portion 24. In the preferred construction, theinsulating material 32 electrically insulates prongs 21 from casing 11and serves to retain prongs 21 and insulator elements 1617 in position.The insulating material 32 includes raised portions 34 about prongs 21which increases the distance from conductor to ground.

1 The ends 30 of heating coil 31 are placed in sockets 27 and areretained by crimping the terminal prong ends 26 as shown in Fig. 4. Theheating coil 31 extends through a series of insulators 33 (Fig. 1)located in tubular structure 10, the insulators 33 operatively spacingthe rows of heating coil 31 from each other and from the tubular casing11.

It is apparent that the heating coil 31 is energized merely by attachinga female plug to the terminal prongs 21 extending outwardly of thecasing end 13 and outwardly of insulating material 32, and by applyingelectric power.

7 Although the invention has been described by making detailed referenceto a single preferred embodiment, such detail is to be understood in aninstructive, rather than in any restrictive sense, many variants beingpossible within the scope of the claims hereunto appended.

We claim as our invention:

1. A terminal structure for a heating unit having a heating coilcomprising a tubular casing including a forward casing end, the casingbeing provided with an annular depressed portion spaced from said casingend to provide a forward chamber and a rearward chamber, a pair ofinsulator elements arranged in end to end abut- Iting relation in saidrearward casing chamber, said insulator elements being provided with aplurality of aligned bores extending from end to end, a plurality ofterminal prongs located in said bores, one of said insulator elementsbeing provided with recesses in said bores adjacent the other element,said prongs being provided with enlarged shoulders received in saidrecesses, adhesive material in said recesses and between abuttingsurfaces of said insulator elements, said adhesive material retainingthe elements together and fixing the shoulders in said recesses, one ofsaid insulator elements having a reduced forward end portion arranged tointerfit said depressed casing portion and to extend partially into saidforward casing chamber, said depressed casing portion engaging the lastsaid insulator element to retain said element in said rearward casingportion, the prongs extending rearwardly of said elements for connectionto the heating coil, the prongs having forward ends extending throughsaid forward casing chamber and outwardly of said casing for selectiveconnection to a female plug, and a molded insulating material disposedin and filling said forward casing chamber about said prongs and reducedforward end of the said one insulator element from the forward end ofthe casing to said insulator element.

2. A waterproof terminal structure for a heating unit having a heatingcoil comprising a tubular casing including a forward casing end, thecasing being provided with an annular depressed portion spaced from saidcasing end to provide a forward chamber and a rearward chamber,insulating means located in said rearward casing chamber, a plurality ofterminal prongs connected to and carried by said insulating means, saidprongs having forward ends extending through said forward casing chamberand outwardly of said casing for selective connection to a female plug,the insulating means having a reduced portion that closely interfits theannular depressed casing portion and extends into the forward casingchamber, the said reduced portion being spaced from the casing definingthe forward casing chamber, said depressed casing portion engaging theinsulating means to retain said means in the said rearward casingchamber, and a molded insulating material disposed in and filling saidforward casing chamber about said prongs and about that reduced portionof the insulating means located in the forward casing chamber from theforward end of the casing to said insulating means.

References Cited in the file of this patent UNITED STATES PATENTS1,857,614 Backer May 10, 1932 2,369,045 Hampton et al. Feb. 6, 19452,383,823 Schmitt Aug. 28, 1945 2,383,926 White Aug. 28, 1945 2,456,343Tuttle Dec. 14, 1948 2,563,713 Frei et al. Aug. 7, 1951 2,788,503 MillisApr. 9, 1957 2,790,153 Arson Apr. 23, 1957 FOREIGN PATENTS 373,452Germany Apr. 12, 1923

